Pneumatic tire including inclined grooves and connection grooves

Abstract

A pneumatic tire comprising a tread portion having a plurality of blocks which are defined by inclined grooves and by a plurality of connection groves connecting with the inclined grooves or with the tread end, wherein the side wall portion of a block facing a first inclined groove coming into contact with the ground precedingly is more rigid than the side wall portion of the same block facing a second inclined groove coming into contact with the ground following the first inclined groove, and the side wall portion of the same block located at the inner side in the tire width direction is more rigid than the side wall portion located at the outer side in the tire width direction.

I claim: 
     
       1. A pneumatic tire comprising; a tread portion having a plurality of inclined grooves which extend outwardly respectively from an inner side of the tire in the width direction to an outer ground contact side oriented at an angle of more than 45° to the tire rotational axis and arranged at intervals along the tire circumferential direction, and a plurality of blocks which are defined by said inclined grooves and by a plurality of connection grooves connecting with said inclined grooves to define a high angle unidirectional block pattern, said inclined grooves coming into contact with the ground in order beginning with the inner side to the outer side, wherein the side wall portion of a block facing a first inclined groove coming into contact with the ground is precedingly more rigid than the side wall portion of said block facing a second inclined groove coming into contact with the ground following the first inclined groove, and the side wall portion of said block located at the inner side in the tire width direction is more rigid than the side wall portion of said block located at the outer side, and wherein angle α1 which is formed between the tread surface and the side wall portion of the block facing the first inclined groove and angle α2 which is formed between the tread surface and the side wall portion of the block facing the second inclined groove satisfy the following expression: α1 >90°≧α2, and angle β1 which is formed between the tread surface and the side wall portion of the block located at the inner side and angle β2 which is formed between the tread surface and the side wall portion of the block located at the outer side satisfy the following expression: β1>90°≧β2. 
     
     
       2. The pneumatic tire according to claim 1, wherein at least the connection groove located at the inner side direction connects substantially orthogonally with the inclined groove. 
     
     
       3. The pneumatic tire according to claim 1, wherein a further groove or slit is arranged at the bottom of the first inclined groove. 
     
     
       4. A pneumatic tire according to claim 1, wherein a further groove or slit is arranged at the bottom of an outer portion in the tire width direction of the connection groove which connects to the first inclined groove. 
     
     
       5. The pneumatic tire according to claim 1, wherein an outer portion in the tire width direction of the connection groove is deeper than an inner portion in the tire width direction of said connection groove. 
     
     
       6. The pneumatic tire of claim 1 wherein said tire is a heavy duty truck or bus tire.